The present invention relates to laser absorption spectroscopy and, more specifically, to correcting laser ramping nonlinearities using an in-line frequency calibration reference for tunable diode laser absorption spectroscopy.
Laser absorption spectroscopy (LAS) may be used to determine an atomic and/or molecular composition of matter by analyzing the frequency properties of laser light passing through an analyte. One popular form of LAS is tunable diode laser absorption spectroscopy (TDLAS). Here, the molecular composition and concentration, as well as other important properties of a gaseous mixture are quantified using a diode laser whose output frequency is systematically changed (“tuned”) within a particular frequency range of interest, where such a range covers a single analyte absorption transition, or a set of analyte absorption transitions in the case where multiple analytes are under investigation.
However, in TDLAS, laser ramping nonlinearities may impact line-shape retrieval and may reduce the efficacy of background removal algorithms.